Chimney flue damper



Oct. 15, H. s. WOODS CHIMNEY FLUE DAMPER Filed Dec. 9, 1937 A iidrneys Patented Oct. 15, 1940 JU TED STATES PATENT OFFICE.

Harold Spry Woods, Portsmouth, N. H. 1 Application December 9, 1937, SerialNo; 178,962

1 Claim,

My invention relates to improvement in chimney fiue dampers. in flues that are connected to all types of furnaces and boilers that are in general usefor the heating of buildings of whatever character and for Whatever purpose, and to improvements in chimney flue dampers in flues connected to steam boilers wherein steam at low pressure is generated for commercial purposes; but it is not applicable on chimneys connected to high-temperature industrial furnaces nor to chimneys connected to high-pressure steam boilers. My chimney fiue damper is operated automatically, electrically, and mechanically; the damper is opened automatically by electrically-motivated commercial mechanism when a commercial thermostat or commercial boiler control or a commercial furnace control operates to close an electric circuit, and the damper is closed by the action of a coil spring under tension.

. The objects of my improvement are; first, to afford a device to apply draft to a fire in a manner recommended by combustion engineers of note, to provide a device for applying draft to a fire only when needed, third, to provide a device to reduce the draft to a predetermined minimum when solid fuels are being burned under conditions commonly designated as a period of bank/f fourth, to provide means for completely stopping draft in the fiuethat is serving automatic oil burners or automatic gas burners, fifth, to provide a device for connecting instantaneously the chimney and the flue serving either a hand-fired coal fire, or an automatic coal stoker, or an automatic oil burner, or an automatic gas burner, sixth, to provide a device that will prevent cold air or an excess amount of cold air being sucked through the furnace setting or the boiler setting by the pull of the chimney during the period when the automatic oil burner or the automatic gas burner is idle, or when the solid fuel fire is on bank, seventh, to afford a device in which the friction opposing the rotation of the damper is greatly reduced, eighth, to provide means for portion of the damper plate and shows the slots into which the'axis fits. Figure 5 is anenlarged view of the gear that changes the straight-line motion of the engaging rack, connected to a commercial solenoid,

to rotary motion. a

- Figure 6 is an enlarged view of the guide for the untoothed portion of the part shown in Fig ure 5.

Figure V7 is an enlarged view partly in section showing the bearing for the damper plate axis.

Figure 8 is an enlarged View of the axis that moves the conical recess shown in Figure '7,

Figure 9 is an end view of Figure 8 and shows a slot into which the damper plate is inserted.

Figure 10 is a section on the line Ill-I0. of Figure 6 and shows the recessed path for the untoothed portion of the gear shown in Figure 5.

Similar numerals refer to similar parts throughout the several views.

The flue I is of regulation length, and it must be of inch or heavier black sheet metal in order to provide the required degree of stiffness; ordinary sheet metal used in flues is too flimsy for the purposes. The bearing 2 and the bearing 6 are: both brazed to flue l and at exactly opposite ends of the same diameter of the flue. Legs or posts M are brazed to the flue and they are 10- cated'approximatelyas shown in Figure 1. All of the above mentio ned parts taken together constitute the framework of the machine.

, Bearing block 3, threaded and recessed on the damper end thereof to form a conical recess whose apex angle is ninety degrees, screws into bearing 2; and axis 4 with a conical end forming an angle of sixty degrees moves in the recess-in bearing block 3. Axis 5 is attached to damper plate 8 and diametrically opposite axis 4 and extends through bearing 6 and sleeve 1 and continues as a drive shaft terminating in a square end to which gear II is attached. Sleeve 1 screws over bearing 6 and acts as a packing sleeve. Damper plate 8 is a circular disk of a diameter smaller than the diameter of the flue I. Semi-circular angle irons 9 are attached to the fiue I only when an automatic oil burner or automatic gas burner is being served by the flue, and they then help to close completely the free area of the flue during the idle periods of the oil burner or gas burner.

Posts l4 support a platform I3 made of transite, a commercial product, to which a suitable commercial solenoid I2 is attached by posts I'I. Posts I4 are threaded over a length sufficient to allow bringing the solenoid I2 into proper alignment with the end of the drive shaft 5, and in platform I3 holes elongated parallel to the length of flue I to receive posts I4 and for posts II other holes elongated in a direction perpendicular to the length of the flue I in connection with the extra threads on the posts I4 allow adjustment of the location. of solenoid I2 in any one or in all three mutually perpendicular directions. Thus, solenoid I2 can be located at exactly the proper point to function correctly with the rack I5, gear II and guide I0.

Fitting over the square end of shaft 5 is the gear II and its teeth mesh with teeth on rack I5. Rack I5 is attached to the plunger in solenoid I2 and moves in a straight line direction under the impulsion of the plunger in solenoid I2, this straight line motion being converted to rotary motion by gear II. It will be observed that the gear I I is but slightly more than a quadrant of a circle f equal diameter. This design is occasioned by the necessity of selecting such a diametral pitch as will rotate the gear II and the damper plate 8 through ninety degrees of arc within the travel distanceof the plunger in solenoid I2.

The guide ID has one long limb and a shorter second limb, the end of the long limb being attached in any suitable manner to the upper end of the rack bar I5 and said rack bar is formed with a notch I5 in one edge'thereof which receives the end of the short leg, as shown in Figure 1. The bight of the guide has a groove or channel therein for receiving the hub of the gear II. The pintle 4 is formed with a slot 4 in its inner end which divides said inner end into a pair of prongs which fit into the slots 6 of the damper plate, see Figure 4. The prongs are fastened in the slots 6' in any suitable manner. The inner end of the shaft which carries the gear II and which forms the axis 5 is connected to the damper plate in the same manner.

When automatic combustion devices of any manufacture and/or type are used in conjunction with this chimney flue damper, I recommend the use of a mercury switch of commerce. Switch arm I6, equipped with a fuse clip, is attached to shaft 5 in such a manner that the switch arm l6 rotates parallel to and in unison with shaft 5, thus opening and closing the mercury switch and thus opening and closing the electric circuit. Also, switch arm I6 is attached to shaft 5 in such manner that the mercury switch cannot close the electric circuit until shaft 5 has rotated to a position where the damper plate 8 to which shaft when the electric circuit is broken by the action of any one of the commercialcontrols such as thermostat, etc. the demands for heat have been satisfied and the damper plate 8 should be closed.

Closing of the damper plate 8 is accomplished by the action of a coil spring I8 attached to the plunger in solenoid I2 and to a post fastened to platform I3, and having a tensile force suficient only to overcome the friction and inertia of the moving parts of the chimney flue damper machine.

The damper plate 8 is designed with a diameter of the flue I to provide an annular space between the flue I and the circumference of the damper plate 8 when the damper plate 8 is in the closed position. The area of the annular space, above mentioned, is that area necessary to allow a predetermined minimum volume of the gases of combustion to escape into the chimney during the period when the coal fire, whether stoked or hand-fired, is banked, i. e., the rate of combustion of the coal is retarded.

I am aware that, prior to my invention, mechanically and/or electrically operated dampers have been made to operate on some automatic principle. I, therefore, do not claim such a combination broadly.

I claim:

A damper device of the class described comprising a pipe section for insertion in a pipe line leading from a furnace to a chimney, a damper in the pipe section including a shaft having one end extending from the pipe section, a segmental gear connected to the extended end of the shaft, posts extending outwardly from a part of the pipe section, a platform of non-conducting material supported by the outer ends of the posts, a solenoid, posts supporting the same from the platform, a plunger passing through the solenoid and having one end extended and formed with rack teeth for engaging the teeth of the gear, spring means connected with the other end of the plunger for normally holding the plunger in a position with the damper closed and a substantially U-shaped guide member connected with the toothed part of the plunger and having a groove in its bight part for receiving portions of the hub of the segmental gear.

HAROLD SPRY WOODS.

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